The oldest known example of a navigational astrolabe

[fernando]

This is not news, on what concerns the event per se. What is new is that the rescued device is indeed an (navigation) astrolabe, in principle the oldest example ever found.
A Portuguese astrolabe, an instrument once used by mariners to measure the altitude of the sun during their voyages.
Recovered from the Esmeralda, sank in 1503 during a storm, near al-Hallaniyah Island, off the Oman coast, in the Arabian Sea.
The Esmeralda was commanded by Vicente Sodré, Vasco da Gama’s maternal uncle, and was part of the 1502 Portuguese armada to India.
The bronze disc measures 17.5cm in diameter and is less than 2mm thick.
Given that it exhibits both the Portuguese coat of arms and the emblem of King Dom Manuel I, it may certainly be dated as being from between 1495-1500.
After a period in which its identification as an astrolabe was only an assumption, it is now recognized as such, after a laser scanning revealed etches around the edge of the disc, each with a five degrees interval.
It is known that, the Portuguese were at the forefront of developing astrolabes at sea.
I wish i had this one in my little collection .

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